A pre-installed World of Warcraft Burning Crusade (2.4.3) client for macOS. Does not include Launcher.app to prevent accidental updates.
You may get an "Unknown Publisher" warning when attempting to launch the game. In System Preferences, open Security & Privacy and Under "Allow apps downloaded from" there should be an "Open Anyway" -- click that.
Mac OS X Lion broke the native client for 2.4.3 due to the drop of Rosetta support. However, seemingly it has begun working again natively on macOS. As of writing this (31/5/2018) it works on macOS High Sierra with the latest updates installed